Immediate loading after implant placement following tooth extraction up‐regulates cellular activity in the dog mandible

Abstract

The aim of this study was to investigate cellular activity of the cervical portion of peri-implant tissue due to immediate loading after implant placement following tooth extraction from the dog mandible, in terms of morphological, immunohistochemical and molecular characteristics. A sand-blasted implant was inserted into the root septum bone of each extraction socket and was connected to a superstructure made from resin and then covered with an expanded polytetrafluoroethylene membrane. Implants without the superstructure were used as the non-loading control group. Animals were sacrificed 1-3 weeks later and specimens were observed using light microscopy and mRNA levels were analyzed by real-time polymerase chain reaction. The new bone formation ratio in the loading group at 3 weeks was significantly higher than in the non-loading group. Alkaline phosphatase (ALP)-positive cells were observed in tissues around the implant surface in both groups at each of the time periods. More osteocalcin (OCN)-positive cells were observed in the non-loading group than in the loading group at 2 weeks. The expression of ALP mRNA in the loading group was significantly up-regulated compared with the non-loading group (P<0.05). The expression of OCN mRNA in the loading group was significantly up-regulated compared with the non-loading group at 2 weeks (P<0.05). These results suggest that immediate loading after implant placement following tooth extraction osteogenic affects cellular activity of cervical portion of peri-implant tissue.